In the processing and packaging of semiconductor devices, wire bonding continues to be the primary method of providing electrical interconnection between two locations within a package (e.g., between a die pad of a semiconductor die and a lead of a leadframe). More specifically, using a wire bonder (also known as a wire bonding machine) wire loops are formed between respective locations to be electrically interconnected.
An exemplary conventional wire bonding sequence includes: (1) forming a free air ball on an end of a wire extending from a bonding tool; (2) forming a first bond on a die pad of a semiconductor die using the free air ball; (3) extending a length of wire in a desired shape between the die pad and a lead of a leadframe; (4) stitch bonding the wire to the lead of the leadframe; and (5) severing the wire. In forming the bonds between (a) the ends of the wire loop and (b) the bond site (e.g., a die pad, a lead, etc.) varying types of bonding energy may be used including, for example, ultrasonic energy, thermosonic energy, thermocompressive energy, amongst others.
The complexity of devices that utilize wire bonding techniques continues to increase, and the complexity of the techniques used to form wire loops also continues to increase. Unfortunately, in certain wire loop shapes, conventional wire looping techniques result in problems such as (a) wire sway, (b) low number of units per hour processed (i.e., UPH), (c) sagging wire loops, particularly adjacent both sides of the last kink of the wire loop, and (d) loops with high “humps.”
Thus, it would be desirable to provide improved methods of forming wire loops.